Fix: resolve the critical issues reported by sonarcube

Change-Id: If94b1a50ba2ac3e4d4e18b524400fda768b2b072
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingSnatHandler.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingSnatHandler.java
index 081c9bd..07cad1e 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingSnatHandler.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingSnatHandler.java
@@ -1343,6 +1343,8 @@
                     break;
                 case OPENSTACK_NODE_REMOVED:
                     eventExecutor.execute(() -> processGatewayRemoval(osNode));
+                    eventExecutor.execute(() -> reconfigureRouters(osNode));
+                    break;
                 case OPENSTACK_NODE_INCOMPLETE:
                 case OPENSTACK_NODE_UPDATED:
                     eventExecutor.execute(() -> reconfigureRouters(osNode));